Heretofore, there is publicly known a technology of a lawn mower including a work device having a plurality of blades for performing lawn mowing work, for example, as disclosed in JP 2013-253510 A.
JP 2013-253510 A discloses a lawn mower including a mower unit that serves as a work device. The mower unit has a plurality of blades. In a case where it is detected that power from an engine is transmitted to the mower unit, the lawn mower can control the engine by isochronous control.
Thus, in a case where power is transmitted to the mower unit, it is determined that the mower unit is in the course of lawn mowing work, and the engine is controlled by isochronous control. Consequently, even when a load applied to the engine is fluctuated, an engine rotational speed can be maintained constant, and the rotation numbers of the plurality of blades can be also maintained constant.
However, in the lawn mower disclosed in JP 2013-253510 A, the plurality of blades are driven through a single belt (belt transmission mechanism), and therefore the plurality of blades rotate at the same rotation number. Accordingly, the lawn mower has room for improvement in energy saving performance. Hereinafter, specific description is made.
Generally, the plurality of blades are disposed side by side in a left and right direction. Therefore, when the lawn mower turns left and right, the speeds of the plurality of blades to the ground are different from each other. Specifically, the speed of a blade disposed on an inner side in a turning direction (hereinafter, simply described as an “inner blade”) is smaller (slower) than the speed of a blade disposed on an outer side in the turning direction (hereinafter, simply described as an “outer blade”). In this case, even when the rotation number of the inner blade is made smaller than the rotation number of the outer blade, it is possible to perform work (lawn mowing work) with respect to the ground with accuracy equal to the outer blade. Therefore, a conventional technology of rotating a plurality of blades at the same rotation number includes inefficient work and has room for improvement in energy saving performance.